Change the allocation of the stdout and stderr collected by Process.runSync

runtime/bin/process_macos.cc

Index: runtime/bin/process_macos.cc
diff --git a/runtime/bin/process_macos.cc b/runtime/bin/process_macos.cc
index 8187026f5655c64d5e82e2fdc13e48ce006e084e..23de1fd525dfce66301f21d56869725aff2db445 100644
--- a/runtime/bin/process_macos.cc
+++ b/runtime/bin/process_macos.cc
@@ -567,23 +567,27 @@ int Process::Start(const char* path,
 }
 
 
-static bool ReadProcessBuffer(uint8_t** buffer,
-                              intptr_t* buffer_length,
-                              intptr_t available,
-                              int fd) {
-  uint8_t* tmp = new uint8_t[*buffer_length + available];
-  if (tmp == NULL) FATAL("Allocation failed");
-  memmove(tmp, *buffer, *buffer_length);
-  delete[] *buffer;
-  *buffer = tmp;
-  intptr_t bytes = TEMP_FAILURE_RETRY(read(
-      fd,
-      reinterpret_cast<void*>(*buffer + *buffer_length),
-      available));
-  if (bytes < 0) return false;
-  *buffer_length += bytes;
-  return true;
-}
+class BufferList: public BufferListBase {
+ public:
+  bool Read(int fd, intptr_t available) {
+    // Read all available bytes.
+    while (available > 0) {
+      if (free_size_ == 0) Allocate();
+      ASSERT(free_size_ > 0);
+      ASSERT(free_size_ <= kBufferSize);
+      intptr_t block_size = dart::Utils::Minimum(free_size_, available);
+      intptr_t bytes = TEMP_FAILURE_RETRY(read(
+          fd,
+          reinterpret_cast<void*>(tail_->data_ + (kBufferSize - free_size_)),
+          block_size));
+      if (bytes < 0) return false;
+      data_size_ += bytes;
+      free_size_ -= bytes;
+      available -= bytes;
+    }
+    return true;
+  }
+};
 
 
 static bool CloseProcessBuffers(struct pollfd fds[3]) {
@@ -605,10 +609,11 @@ bool Process::Wait(intptr_t pid,
   // Close input to the process right away.
   VOID_TEMP_FAILURE_RETRY(close(in));
 
-  uint8_t* out_data = NULL;
-  intptr_t out_data_length = 0;
-  uint8_t* err_data = NULL;
-  intptr_t err_data_length = 0;
+  // There is no return from this function using Dart_PropagateError
+  // as memory used by the buffer lists is freed through their
+  // destructors.
+  BufferList out_data;
+  BufferList err_data;
   union {
     uint8_t bytes[8];
     int32_t ints[2];
@@ -629,6 +634,8 @@ bool Process::Wait(intptr_t pid,
     if (TEMP_FAILURE_RETRY(poll(fds, alive, -1)) <= 0) {
       return CloseProcessBuffers(fds);
     }
+
+    // Process incoming data.
     for (int i = 0; i < alive; i++) {
       if (fds[i].revents & POLLIN) {
         intptr_t avail = FDUtils::AvailableBytes(fds[i].fd);
@@ -636,15 +643,14 @@ bool Process::Wait(intptr_t pid,
         // bytes. POLLHUP is most likely also set in this case.
         if (avail > 0) {
           if (fds[i].fd == out) {
-            if (!ReadProcessBuffer(&out_data, &out_data_length, avail, out)) {
+            if (!out_data.Read(out, avail)) {
               return CloseProcessBuffers(fds);
             }
           } else if (fds[i].fd == err) {
-            if (!ReadProcessBuffer(&err_data, &err_data_length, avail, err)) {
+            if (!err_data.Read(err, avail)) {
               return CloseProcessBuffers(fds);
             }
           } else if (fds[i].fd == exit_event) {
-            intptr_t avail = FDUtils::AvailableBytes(fds[i].fd);
             if (avail == 8) {
               intptr_t b = TEMP_FAILURE_RETRY(read(fds[i].fd,
                                                    exit_code_data.bytes, 8));
@@ -655,10 +661,12 @@ bool Process::Wait(intptr_t pid,
           } else {
             UNREACHABLE();
           }
-          continue;
         }
       }
+    }
 
+    // Process closed.
+    for (int i = 0; i < alive; i++) {
       if (fds[i].revents & POLLHUP) {
         VOID_TEMP_FAILURE_RETRY(close(fds[i].fd));
         alive--;
@@ -670,8 +678,8 @@ bool Process::Wait(intptr_t pid,
   }
 
   // All handles closed and all data read.
-  result->SetStdoutData(out_data, out_data_length);
-  result->SetStderrData(err_data, err_data_length);
+  result->set_stdout_data(out_data.GetData());
+  result->set_stderr_data(err_data.GetData());
 
   // Calculate the exit code.
   intptr_t exit_code = exit_code_data.ints[0];